title: Novel antifungal α-hairpinin peptide from Stellaria media seeds: structure, biosynthesis, gene structure and evolution.
abstract: Plant defense against disease is a complex multistage system involving initial recognition of the invading pathogen, signal transduction and activation of specialized genes. An important role in pathogen deterrence belongs to so-called plant defense peptides, small polypeptide molecules that present antimicrobial properties. Using multidimensional liquid chromatography, we isolated a novel antifungal peptide named Sm-AMP-X (33 residues) from the common chickweed (Stellaria media) seeds. The peptide sequence shows no homology to any previously described proteins. The peculiar cysteine arrangement (C(1)X3C(2)XnC(3)X3C(4)), however, allocates Sm-AMP-X to the recently acknowledged α-hairpinin family of plant defense peptides that share the helix-loop-helix fold stabilized by two disulfide bridges C(1)-C(4) and C(2)-C(3). Sm-AMP-X exhibits high broad-spectrum activity against fungal phytopathogens. We further showed that the N- and C-terminal "tail" regions of the peptide are important for both its structure and activity. The truncated variants Sm-AMP-X1 with both disulfide bonds preserved and Sm-AMP-X2 with only the internal S-S-bond left were progressively less active against fungi and presented largely disordered structure as opposed to the predominantly helical conformation of the full-length antifungal peptide. cDNA and gene cloning revealed that Sm-AMP-X is processed from a unique multimodular precursor protein that contains as many as 12 tandem repeats of α-hairpinin-like peptides. Structure of the sm-amp-x gene and two related pseudogenes sm-amp-x-ψ1 and sm-amp-x-ψ2 allows tracing the evolutionary scenario that led to generation of such a sophisticated precursor protein. Sm-AMP-X is a new promising candidate for engineering disease resistance in plants.
authors.affiliation: Vavilov Institute of General Genetics, Russian Academy of Sciences, ul. Gubkina 3, 119991, Moscow, Russian Federation, annslav82@gmail.com.
authors.forename: Anna A
authors.initials: AA
authors.lastname: Slavokhotova
authors.forename: Eugene A
authors.initials: EA
authors.lastname: Rogozhin
authors.forename: Alexander K
authors.initials: AK
authors.lastname: Musolyamov
authors.forename: Yaroslav A
authors.initials: YA
authors.lastname: Andreev
authors.forename: Peter B
authors.initials: PB
authors.lastname: Oparin
authors.forename: Antonina A
authors.initials: AA
authors.lastname: Berkut
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Vassilevski
authors.forename: Tsezi A
authors.initials: TA
authors.lastname: Egorov
authors.forename: Eugene V
authors.initials: EV
authors.lastname: Grishin
authors.forename: Tatyana I
authors.initials: TI
authors.lastname: Odintsova
mesh_terms: D000595:Amino Acid Sequence; D000935:Antifungal Agents / Q000737:chemistry / Q000378:metabolism*; D003001:Cloning, Molecular; D019143:Evolution, Molecular; D005658:Fungi / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012639:Seeds / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D029752:Stellaria / Q000737:chemistry* / Q000378:metabolism
chemical_list: D000935:Antifungal Agents; D010940:Plant Proteins